title: Effect of quercetin and glucuronide metabolites on the monoamine oxidase-A reaction in mouse brain mitochondria.
abstract: OBJECTIVE
  Quercetin is a flavonoid found in plant foods and herbal medicines. It possesses antidepressant-like effects in forced swimming test-loaded rodents. We wanted to clarify the mechanism of action of dietary quercetin for exerting antidepressant-like effects. The effect of quercetin and its antioxidative metabolite quercetin 3-glucuronide (Q3GA) on the activity of mouse brain mitochondrial monoamine oxidase-A (MAO-A) was evaluated by measuring the deamination product of serotonin, 5-hydroxyindole acetaldehyde (5-HIAL).
  
  
  METHODS
  An ultraviolet high-performance liquid chromatographic analysis was applied to measure the 5-HIAL generated by the reaction of MAO-A with serotonin. The inhibitory effect of quercetin and Q3GA on mitochondrial MAO-A activity was estimated by the content of 5-HIAL and hydrogen peroxide accompanied by the MAO-A reaction.
  
  
  RESULTS
  Quercetin (but not Q3GA) decreased the production of 5-HIAL by MAO-A activity. Q3GA inhibited the generation of hydrogen peroxide from the MAO-A reaction with serotonin. A periodic forced swimming test in mice increased brain mitochondrial MAO-A activity. Brain mitochondrial MAO-A activity was decreased in mice administered quercetin for 7 d, but its effect was much weaker than that of the selective MAO-A inhibitor clorgyline.
  
  
  CONCLUSIONS
  Quercetin is effective in the modulation of serotonergic activity by attenuating mitochondrial MAO-A activity in the brain. Its antioxidative metabolite Q3GA attenuates oxidative stress by interrupting the generation of hydrogen peroxide accompanying the MAO-A reaction.
authors.affiliation: Department of Food Science, Graduate School of Nutrition and Bioscience, Institute for Health Biosciences, University of Tokushima, Tokushima, Japan.
authors.forename: Saki
authors.initials: S
authors.lastname: Yoshino
authors.forename: Aya
authors.initials: A
authors.lastname: Hara
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sakakibara
authors.forename: Kyuichi
authors.initials: K
authors.lastname: Kawabata
authors.forename: Akira
authors.initials: A
authors.lastname: Tokumura
authors.forename: Akari
authors.initials: A
authors.lastname: Ishisaka
authors.forename: Yoshichika
authors.initials: Y
authors.lastname: Kawai
authors.forename: Junji
authors.initials: J
authors.lastname: Terao
mesh_terms: D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D020719:Glucuronides / Q000378:metabolism / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism; D006897:Hydroxyindoleacetic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D008995:Monoamine Oxidase / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D011794:Quercetin / Q000031:analogs & derivatives / Q000494:pharmacology* / Q000627:therapeutic use; D012701:Serotonin / Q000378:metabolism; D013315:Stress, Psychological / Q000188:drug therapy / Q000378:metabolism; D013550:Swimming
chemical_list: D000928:Antidepressive Agents; D020719:Glucuronides; D008996:Monoamine Oxidase Inhibitors; D010936:Plant Extracts; C004277:hydroxyindoleacetaldehyde; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D011794:Quercetin; D006861:Hydrogen Peroxide; D008995:Monoamine Oxidase